CN104809311A - Structural part remaining life predicting method based on multi-factor fusion correction - Google Patents

Abstract

The invention discloses a structural part remaining life predicting method based on multi-factor fusion correction. By taking multiple factors influencing the structural part remaining life into account, the structural part remaining life predicting method comprises the following steps: measuring and correcting stress intensity and residual stress of a structural part, calculating stress ratio, calculating size correcting parameters, selecting stress concentration correcting parameters and surface manufacturing quality correcting parameters, and the like. By the structural part remaining life predicting method, the accuracy of a prediction result is greatly improved, so that accurate and effective prediction of the structural part remaining life is achieved.

Description

A kind of based on the multifactor structural member method for predicting residual useful life merging correction

Technical field

The invention belongs to mechanical detection field, especially a kind of structural member Crack Extension Forecasting Methodology.

Background technology

Along with the progress of society, large number quipments is all towards the future development maximized.Under such background prerequisite, small fault will cause huge loss, therefore predicts it is necessary and urgent to the residual life of equipment or component.Along with the development of science and technology, the understanding of people to this subject tired is more deep, and a series of Prediction method for fatigue life is obtained widespread use: as nominal stress method, Local Stress Strain Method, critical section domain method etc.Critical section domain method is the fatigue life evaluation method that a class has future in engineering applications.Stress standard-field strength method and critical distance method have obtained some application as two class methods common in the domain method of critical section.Then be more prone in engineering reality use nominal stress method and Local Stress Strain Method.The great advantage of tradition nominal stress method is that analytical procedure is simple, widely applicable and practical.Local Stress Strain Method, based on strain analysis, replaces S-N curve with strain life-span ε-N curve and stress-strain curve under being equipped with CYCLIC LOADING carrys out predicted fatigue life.These existing forecasting techniquess mainly have the following disadvantages: (1) stress standard-field strength method and critical distance method are mostly only for planar structure, and also little (2) using structural member as analytic target are for traditional nominal stress method, because the fatigue behaviour parameter between structural member and material sample there are differences, so the estimation precision of fatigue lifetime cannot be guaranteed.(3) estimation precision of Local Stress Strain Method is higher, but its applicable surface is narrower.

Therefore, need a kind of new technical scheme to solve the problem.

Summary of the invention

In order to overcome problems of the prior art, the invention provides a kind of based on the multifactor structural member method for predicting residual useful life merging correction.

For achieving the above object, the present invention can adopt following technical scheme:

Merge based on multifactor the structural member method for predicting residual useful life revised, it is characterized in that: the method comprises the following steps:

S1. the calculating of structural member stress intensity:

Set up the three-dimensional model of structural member, and use the stress intensity of finite element analysis software to three-dimensional model to analyze;

S2. the measurement of unrelieved stress and correction:

The distribution obtaining its unrelieved stress is measured to the unrelieved stress of the structural member of entity, and measurement result is substituted into together with the result of calculation of S1 correction formula and complete correction;

S3. the stress ratio based on segmenting principle calculates:

According to the non-regularity random load course under the actual condition gathered, segmentation principle is adopted to calculate stress ratio;

S4. the calculating of Dimension correction parameter:

According to the Dimension correction parameter corresponding to the result of calculation of S1 and the stress state distribution computation structure part of material sample;

S5. stress concentrates the calculating of corrected parameter:

Choose suitable stress field path of integration according to the result of calculation of S1, under the best total of points path being equivalent to stress slowly-releasing region, calculated stress concentrates corrected parameter;

S6. surface manufactures choosing of crudy corrected parameter:

Determine technology type, and select and manufacture crudy corrected parameter according to the skin hardness of actual measurement with the surface corresponding to structural member;

S7. based on the structural member predicting residual useful life of multifactor correction:

The result of calculation of S1-S6 is substituted into the prediction completing structural member residual life based on the structural member predicting residual useful life algorithm of multifactor correction.

Compared with prior art, the present invention can take into account all the many factors that structural member impacts fatigue lifetime, and by aforesaid operations step thus the few drawback of the Consideration that can effectively avoid prior art to exist, the precision that predicts the outcome is greatly improved, thus realizes the accurate and effective prediction of structural member residual life.

Accompanying drawing explanation

Fig. 1 the present invention is based on the multifactor FB(flow block) merging the structural member method for predicting residual useful life revised.

Embodiment

Refer to shown in Fig. 1, the invention discloses a kind of based on the multifactor structural member Crack Extension Forecasting Methodology merging correction.

The method comprises the following steps:

Merge based on multifactor the structural member method for predicting residual useful life revised, it is characterized in that: the method comprises the following steps:

S1. the calculating of component stress intensity

The three-dimensional model analyzing component is set up according to drawing, three-dimensional model after setting up is imported in finite element software, arrange by stress and strain model, constraint, load applying step completes the pre-treatment of component finite element analysis, finite element analysis software is used to analyze its stress intensity after treating pre-treatment, to obtain the distribution of its stress state;

S2. the measurement of unrelieved stress and correction

The unrelieved stress of entity component is measured to the residual stress distribution state obtained corresponding to structural member, and measurement result is substituted into together with the result of calculation of S1 correction formula 1 and complete correction;

${\mathrm{\σ}}^r={\mathrm{\σ}}_R-\left(\frac{{\mathrm{\σ}}_R}{{\mathrm{\σ}}_{\mathrm{bb}}}\right)\frac{(1+r)\·{\mathrm{\σ}}_{\max }}{2}={\mathrm{\σ}}_R-(1-w)\·\frac{(1+r){\·\mathrm{\σ}}_{\max }}{2}---\left(1\right)$

In formula: σ ^rfor based on the revised stress amplitude of unrelieved stress; σ _maxfor maximum stress; R is stress ratio; σ _bbfor tensile strength; σ _rfor the analytic intensity of correspondence; W is that rich stress slowly-releasing puts sensitivity coefficient.

S3. the stress ratio based on segmenting principle calculates

According to the non-regularity random load course under the actual condition gathered, segmentation principle is adopted to calculate stress ratio.

(t is there is for one _i, σ _i) loading spectrum of corresponding relation, its mean stress σ _mcan be expressed as:

${\mathrm{\σ}}_m=\frac{{\mathrm{\σ}}_1+{\mathrm{\σ}}_2+...+{\mathrm{\σ}}_n}{n}---\left(2\right)$

Wherein loading spectrum can be expressed as σ _i=f (t _i), make f (t)=σ _m, can mean stress σ be corresponded to _mtime component t _q(q=1,2,3......m).

Due to the cycle characteristics of load, choose two points on a timeline successively according to the time sequencing on loading spectrum, then then form (t after segmentation being carried out to it according to the cycle characteristics of loading spectrum ₀, t ₂), (t ₂, t ₄), (t ₅, t ₇) ....Namely in segment data, at least there are 2 points, make σ _t> σ _mand σ _t+1< σ _m.

Solve by formula 3 counter stress ratio again after treating segmentation

$r=\frac{{\mathrm{\&sigma;}}_{\min }^{\&prime;}}{{\mathrm{\&sigma;}}_{\max }^{\&prime;}}---\left(3\right)$

S4. the calculating of Dimension correction parameter

Stress state distribution situation corresponding to the result of calculation of S1 and material sample is substituted into the Dimension correction parameter of formula 4 computation structure part;

$\mathrm{\&epsiv;}=\frac{\underset{0}{\overset{L}{\&Integral;}}(B_1+B_2{L}^{\&prime;}+B_3{L}^{\&prime;2}+B_4{L}^{\&prime;3})\mathrm{dL}}{\underset{0}{\overset{L}{\&Integral;}}(A_1+A_{2}L+A_3{L}^2+A_4{L}^3)\mathrm{dL}}---\left(4\right)$

Stress field function also represents apart from the distance L (i) of maximum local stress root by certain point under stress integration path in stress field, namely

f(x ₁,x ₂)＝A ₁+A ₂L(i)+A ₃L ²(i)+A ₄L ³(i) (5)

In formula, A ₁, A ₂, A ₃, A ₄and B ₁, B ₂, B ₃, B ₄represent the coefficient in fitting function expression formula.Shown in (4), structural member Dimension correction parameter is the ratio of stress field functional integration between structural member and reference standard sample.

S5. stress concentrates the calculating of corrected parameter

Choose suitable stress field path of integration according to the result of calculation of S1, under the best total of points path being equivalent to stress slowly-releasing region, calculated stress concentrates corrected parameter;

Its concrete solution procedure comprises:

1) according to the result of calculation of S1, the xsect along maximum stress chooses the path of integration of reflection Stress Field Distribution.

2) get on path of integration a little, point on stress root section direction can be obtained and, apart from the respective value between L and stress s, corresponding stress field function expression can be obtained by the above-mentioned data of matching.

3) stress field function expression is substituted into following formula, solves and the nominal stress corresponding to stress field:

$s_n=\frac{{\&Integral;}_0^{L}S\left(L\right)\mathrm{dL}}{L}=\frac{\underset{i=0}{\overset{n-1}{\mathrm{\&Sigma;}}}{\&Integral;}_{L_i}^{L_{i+1}}{S}_i\left(L\right)\mathrm{dL}}{L}---\left(6\right)$

In formula, $L=\underset{i=0}{\overset{n}{\mathrm{\&Sigma;}}}{L}_i.$

4) nominal stress is substituted into following formula, the stress obtained corresponding to structural member concentrates corrected parameter:

$K_t=\frac{s_{\max }}{s_n}---\left(7\right)$

S6. surface manufactures choosing of crudy corrected parameter

Determine main technology type according to manufacturing process card, and go out according to the data decimation such as skin hardness of actual measurement and manufacture crudy corrected parameter with the surface corresponding to structural member;

Surface corresponding to the common processing mode of table 1 manufactures crudy corrected parameter

S7. based on the structural member predicting residual useful life of multifactor correction

On the basis completing above-mentioned computation process, the result of calculation of S1-S6 is substituted into the prediction completing structural member residual life based on the structural member predicting residual useful life algorithms 8 of multifactor correction.

${(\frac{{\mathrm{\&sigma;}}^r}{K_t}\&CenterDot;\mathrm{\&epsiv;}\&CenterDot;\mathrm{\&beta;})}^m\&CenterDot;N=C---\left(8\right)$

Wherein σ ^rfor based on the revised stress amplitude of unrelieved stress; K _tfor stress concentrates corrected parameter; ε is Dimension correction parameter; β is surface quality corrected parameter; N is fatigue lifetime; M, C are the parameter relevant with material, stress ratio.

Further technical scheme of the present invention is: in described step S2, comprises following concrete operation:

According to the size of stress amplitude, S2.1, according to the result of calculation of S1, determines that the relation of numerical value fatigue lifetime determines the regional extent needing in structural member to carry out focus measurement unrelieved stress;

S2.2 carries out electropolishing to region fixed in S2.1.According to optimum current and the voltage parameters of the actual conditions determination polishing process of structural member, and this best parameters is adopted to complete the polishing of structural member critical area;

S2.3 carries out the measurement of unrelieved stress to the processed complete region of S2.2.According to optimum measurement method, gate time and peak location method in the actual conditions determination residual stress measurement process of structural member, and this best parameters is adopted to complete the test of the unrelieved stress of structural member critical area;

S2.4 carries out data statistics to synthesize three-dimension parameter design distribution plan to the result of S2.3, and substitutes into correction formula to complete makeover process together with the analysis result of S1 by analyzing the three-dimensional Stress Distribution result obtained.。

In addition, a lot, the above is only the preferred embodiment of the present invention for concrete methods of realizing of the present invention and approach.It should be pointed out that for those skilled in the art, under the premise without departing from the principles of the invention, can also make some improvements and modifications, these improvements and modifications also should be considered as protection scope of the present invention.The all available prior art of each ingredient not clear and definite in the present embodiment is realized.

Claims (7)

1. merge based on multifactor the structural member method for predicting residual useful life revised, it is characterized in that: the method comprises the following steps:

S1. the calculating of structural member stress intensity:

Set up the three-dimensional model of structural member, and use the stress intensity of finite element analysis software to three-dimensional model to analyze;

S2. the measurement of unrelieved stress and correction:

The distribution obtaining its unrelieved stress is measured to the unrelieved stress of the structural member of entity, and measurement result is substituted into together with the result of calculation of S1 correction formula and complete correction;

S3. the stress ratio based on segmenting principle calculates:

According to the non-regularity random load course under the actual condition gathered, segmentation principle is adopted to calculate stress ratio;

S4. the calculating of Dimension correction parameter:

According to the Dimension correction parameter corresponding to the result of calculation of S1 and the stress state distribution computation structure part of material sample;

S5. stress concentrates the calculating of corrected parameter:

Choose suitable stress field path of integration according to the result of calculation of S1, under the best total of points path being equivalent to stress slowly-releasing region, calculated stress concentrates corrected parameter;

S6. surface manufactures choosing of crudy corrected parameter:

Determine technology type, and select and manufacture crudy corrected parameter according to the skin hardness of actual measurement with the surface corresponding to structural member;

S7. based on the structural member predicting residual useful life of multifactor correction:

The result of calculation of S1-S6 is substituted into the prediction completing structural member residual life based on the structural member predicting residual useful life algorithm of multifactor correction.

2. according to claim 1 based on the multifactor structural member method for predicting residual useful life merging correction, it is characterized in that: in described step S2, comprise following concrete operation:

According to the size of stress amplitude, S2.1, result of calculation according to S1, determine that the relation of numerical value fatigue lifetime determines the regional extent needing in structural member to carry out focus measurement unrelieved stress;

S2.2, electropolishing is carried out to fixed region in 2.1;

S2.3, the processed complete region of S2.2 is carried out to the measurement of unrelieved stress;

S2.4, data statistics is carried out to synthesize three-dimension parameter design distribution plan to the result of S2.3, and substitute into correction formula to complete makeover process together with the analysis result of S1 by analyzing the three-dimensional Stress Distribution result obtained.

3. according to claim 1 based on the multifactor structural member method for predicting residual useful life merging correction, it is characterized in that:

In S2, described correction formula is:

${\mathrm{\&sigma;}}^r={\mathrm{\&sigma;}}_R-\left(\frac{{\mathrm{\&sigma;}}_R}{{\mathrm{\&sigma;}}_{\mathrm{bb}}}\right)\frac{(1+r){\mathrm{\&sigma;}}_{\max }}{2}={\mathrm{\&sigma;}}_R-(1-w)\&CenterDot;\frac{(1+r)\&CenterDot;{\mathrm{\&sigma;}}_{\max }}{2};$

σ ^rfor based on the revised stress amplitude of unrelieved stress; σ _maxfor maximum stress; R is stress ratio; σ _bbfor tensile strength; σ _rfor the analytic intensity of correspondence; W is that rich stress slowly-releasing puts sensitivity coefficient.

4. according to claim 1 based on the multifactor structural member method for predicting residual useful life merging correction, it is characterized in that:

In S3, the method adopting segmentation principle to calculate stress ratio is:

(t is there is for one _i, σ _i) loading spectrum of corresponding relation, its mean stress σ _mcan be expressed as:

${\mathrm{\&sigma;}}_m=\frac{{\mathrm{\&sigma;}}_1+{\mathrm{\&sigma;}}_2+...+{\mathrm{\&sigma;}}_n}{n}$

Wherein loading spectrum is expressed as σ _i=f (t _i), make f (t)=σ _m, can mean stress σ be corresponded to _mtime component t _q, q=1,2,3......m;

Due to the cycle characteristics of load, choose two points on a timeline successively according to the time sequencing on loading spectrum, then then form (t after segmentation being carried out to it according to the cycle characteristics of loading spectrum ₀, t ₂), (t ₂, t ₄), (t ₅, t ₇) ...; Namely in segment data, at least there are 2 points, make σ _t> σ _mand σ _t+1< σ _m;

Stress ratio r is obtained after treating segmentation

$r=\frac{{\mathrm{\&sigma;}}_{\min }^{\&prime;}}{{\mathrm{\&sigma;}}_{\max }^{\&prime;}}.$

5. according to claim 1 based on the multifactor structural member method for predicting residual useful life merging correction, it is characterized in that:

In S4, Dimension correction parameter is

$\mathrm{\&epsiv;}=\frac{\underset{0}{\overset{L}{\&Integral;}}(B_1+B_2{L}^{\&prime;}+B_3{L}^{\&prime;2}+B_4{L}^{\&prime;3})\mathrm{dL}}{\underset{0}{\overset{L}{\&Integral;}}(A_1+A_{2}L+A_3{L}^2+A_4{L}^3)\mathrm{dL}}$

Structural member Dimension correction parameter is the ratio of stress field functional integration between structural member and reference standard sample;

Stress field function also represents apart from the distance L (i) of maximum local stress root by certain point under stress integration path in stress field, namely

f(x ₁,x ₂)＝A ₁+A ₂L(i)+A ₃L ²(i)+A ₄L ³(i)

In formula, A ₁, A ₂, A ₃, A ₄and B ₁, B ₂, B ₃, B ₄represent the coefficient in fitting function expression formula.

6. according to claim 1 based on the multifactor structural member method for predicting residual useful life merging correction, it is characterized in that:

In S5, stress concentrates the concrete solution procedure of the calculating of corrected parameter to comprise:

1), according to the result of calculation of S1, the xsect along maximum stress chooses the path of integration of reflection Stress Field Distribution;

2), get on path of integration a little, point on stress root section direction can be obtained and, apart from the respective value between L and stress s, corresponding stress field function expression can be obtained by the above-mentioned data of matching;

3), by stress field function expression substitute into following formula, solve and the nominal stress corresponding to stress field:

$s_n=\frac{{\&Integral;}_0^{L}S\left(L\right)\mathrm{dL}}{L}=\frac{\underset{i=0}{\overset{n-1}{\mathrm{\&Sigma;}}}{\&Integral;}_{L_i}^{L_{i+1}}{S}_i\left(L\right)\mathrm{dL}}{L}$

In formula, $L=\underset{i=0}{\overset{n}{\mathrm{\&Sigma;}}}{L}_i;$

4) nominal stress is substituted into following formula, the stress obtained corresponding to structural member concentrates corrected parameter:

$K_t=\frac{s_{\max }}{s_n}.$

7. according to claim 1 based on the multifactor structural member method for predicting residual useful life merging correction, it is characterized in that:

The prediction of structural member residual life is obtained by following formula

${(\frac{{\mathrm{\&sigma;}}^r}{K_t}\&CenterDot;\mathrm{\&epsiv;}\&CenterDot;\mathrm{\&beta;})}^m\&CenterDot;N=C$

Wherein σ ^rfor based on the revised stress amplitude of unrelieved stress; K _tfor stress concentrates corrected parameter; ε is Dimension correction parameter; β is surface quality corrected parameter; N is fatigue lifetime; M, C are the parameter relevant with material, stress ratio.